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The pyrolysis of dimethyl carbonate
Item Type text; Thesis-Reproduction (electronic)
Authors Olson, Dan Allen Herman, 1913-
Publisher The University of Arizona.
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Link to Item http://hdl.handle.net/10150/553376
http://hdl.handle.net/10150/553376
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TEE PYROLYSIS OF DIMETHYL CARBONATE
%y
Dan A. H. Olson
A Thesissmh®tttea to the faculty of the
Department of Chemistryy-'.': "--
in partial fulfillment ofthe requirements.for the degree of
' ■
Master of Science
in the Graduate College Univoreity of Arizona
1938
Approved:Major Profos®or
m* ' ■Date.
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/ 9 3 Z
2-
ACOTOWLEDGKEHT
fhe author wishes to express his * most sincere appreciation for
the advice and assistance of Dr. lathrop E. Heherts, under whose
direction this investigation
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TABLE OF CCBtHTTS
latrofluotionPreparation of the MaterialVapor Pressure of
Dimethyl CarbonateThe Apparatus and Its Use
The ThermostatThe ThermocoupleThe Compressed Air AgitatorThe
Apparatus for following the Pressure Change
Qualitative Analysis of the Products Quantitative Analysis of
the Products
Experimental Data Tables of Kinetic Data Discussion and
Conclusions
Bibliography
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1
Introduction' - '■ ' . / -
Stoichiometric equations, though useful in representing the
overall cburse of a reaction, throw little light on the mechanism
of the reaction, A determination of the actual steps; takei^hy a
reaction from the initial to finalstate is test don# through
kinetic studies.
:•! . /:! ‘ ‘Kinetic studies of reaction in the gaseous phase
are tobe preferred^to/those in the liquid phase, since our
know-
' : /ledge of the Ihwo governing the behavior of gases is much;
' 'more extensive thanrit is for liquids,1 Ihe fundamental Maxwell
distribution law gives the distribution at the velocities of the
molecules.% From it can be determined the relationships between.the
root mean square velocity, the arithmetic mean velocity, and the
most probable velocity. Further extensions give us the number of
collisions per second per c.c., the mean free path of molecules,
etc* From specific heats and band; spectra can be obtained
information on the types of motion exhibited by molecules.3
No such quantitative treatment has been made for liquids.1
Furthermore, complicating factors like solvation, association,
ionisation, wide variation of dielectric constant, etc., make exact
treatment difficult.
However, even in the gaseous phase, treatment of reactions may
not be very simple. The quantitative treatment
; * ' . ' ' ' -
of the behavior of gases is usually based on ideal
condition®
, :
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8
to whleto real gses approach more or less closely, depending
upon the attenuation and nearness to critical points. Them* too*
the reaction Itself may not follow any single path homogeneously,
but be complicated by being in whole or in part heterogeneous due
to reaction on the walls of the confining vessel. Again, there may
be side reactions* opposing reactions, consecutive reactions,
catalysis by the reaction produets, and the like, which reader
mathematical treatment very difficult even when the qualitative
nature of the reaction is known.
Present knowledge indicates that the more complex molecules are
likely to decompose unimoleeularly and homogeneously.4 Since
homogeneous animolecular reactions are of particular interest in
testing theories of activation by collision* it seems desirable
that complex molecules be made the subject for study.
On such considerations* Claudio Alvares-Tostado selected *e8c0g
for study.5 He expected it to decompose unimoleeularly and
homogeneously because of the feet that dimethyl ether decomposes
unimoleeularly at higher temperatures and blmoleeu- larly at lower
temperature®. Actually he found that the primary decomposition was
catalyzed by the wall of the reaction vessel, although the reaction
must be in part homogeneous since the increase in velocity in a
packed flask over an unpacked flask was not as great as that of the
surface-volume ratio. He concluded that the primary decomposition
taking
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3
place at 500° gave C02 and (CH^tgO which then decomposed
Into
CO, CH4, and Hg. He also eappoeed that ethane was formed in
small amounts hy a side reaction, Dae to lack of time he was not
able to make quantitative analyses at various stages of the
decomposition, to correlate the analytical data with the kinetic
data, and thereby set up a mathematical expression describing the
reaction. It was. the purpose of the investigation described in
this paper to make the necessary qualitative and quantitative
analyses to work out the reaction mechanism. He other work on the
deoompecliton of dimethyl carbonate Is known except that of nice
and Johnston6 who found that the molecule decomposes Into free
radicals at 700°-800e, but did not determine what the producte
were.
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4
Preparation of the Material
% e dimethyl carbonate used was obtained from the last- man
Kodak Company, Tests for chloride were made by hydrolysis in
chloride free EaOH with subsequent acidification with HEOg and
addition of AgHOg, Considerable precipitate was
formed. Test of the carbonate used by Tostado also revealed the
presence of Cl but to a lesser extent• The whole of the carbonate
on hand was washed with a 10^ aqueous solution of AgUOg,
separated.from the solution and precipitate by use of
a separating funnel and dried with fused. CaClg, It was then
refluxed over dry PbO and AgEOg for several hours until 0,4
e,e* of the carbonate gave only the faintest opalescence when
tested for CITY The carbonate was decanted off the PbO and
fractionally distilled by use of a Glinsky fractionating tower and
spiral condenser cooled with ice water. The fraction boiling
860-87.2° at ca. 700 m.m, was collected.
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5
The Vapor Pressure of Piciothyl Carbonate
At one stage of the investigation it seemed Sesirafcle to Imew
the vapor pressure of MegCOg from about its melting
point to its boiling point* Accordingly an apparatus was set up
for determining the.vapor pressure by the Ramsey-Young method.7
later was used as the heating medium and ice for cooling. The
temperature was read with a l/lO° thermometer. The following
results v/ei^jobtained;
? in sum. T°C.20*5 8.138.0 . 18.185.5 85.8145. . 44.0198.
61.5250. 57.5SOB. 62.4860 ... ■ ' ' : 66.S .407. 70.9477. •75.3546.
79.1612. v 82.4651. 84.4659. 86.5
A graph of the results is given in Figure I. Ho claim is made
for high aeoaraey.
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yo-t
* 9
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6
The Apparatus and Its ffse
One ef the eoaHaeaest methods of studying the kinetics of a
reaction is by following the pressure change with time, This was
the method used by Tostado in obtaining the results on dimethyl
carbonate already mentioned* Later this apparatus mas improved by
fihodes® for the study of dimethyl sulfite, The apparatus used for
the present investigation is an improvement and simplification of
that used by Rhodes, This apparatus possesses the advantages of
that used by Rhodes in that:
1. The exact time of introduction of a weighed amount of
carbonate can be determined.
2. The reacting gas cones into contact with no surface except
pyrex glass, except for about 2 sq. mm. of Hg. and2 sa* ram. of
stopcock grease in the cooler part of the apparatus. {Ho stopcock
grease was present in Rhodes*b apparatus.)
5. All gas can be maintained at a uniform temperature with the
exception of a small amount in the external capillaries which are
heated well above the boiling point of the carbonate by resistance
wire wrapped around them.
4.. The pressure produced in the reaction flask by the
decomposing carbonate can be read at any desired time without
delay.
5. The temperature can be maintained nearly constant over a
period of several hours.
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f
lia addition the apparatus has the following aivaotages over
that asad by Rhodes:
1# Several short runs can be made each day and without the
meaessity of dismantling the apparatus between each ram.
2. Duplication of experimental conditions for successive runs is
easy to maintain. Hence drifts in the speed of the reaction are
easy to detect.
8. The furnace need mot be opened when sample is in- troduced,
thereby avoiding the drop in temperature during the irtbial stages
of the decomposition.
4. The products can be quickly and easily removed from reaction
vessel at any time.
5. The undecompoeed ester can be removed from the reaction
products.
6. large amounts of products can be collected for ena-: - ' . .
. . '
lysis.7. Final pressures of two atmospheres can be reached.8.
The reaction flask can be opened to the atmosphere
at any time between runs for removal of any Eg vapor or for
glass blowing without disturbing other parts of the apparatus*
The apparatus consists of the following.
The Thermostat. :The thermostat is the same as that described by
Rhodes
with the exception that the heating coils on the bottom of the
fumoee were removed and the depth of infusorial earth reduced to
about § inch to cut down the temperature gradient.
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8
Moreover, the theretostat is not moved or opened at the
beginning of the rune* .
The Thermocouple.The five junction, Hichrome-Advance
thermocouple for
measuring temperatures nas the same as used by Rhodes. Hie E. Um
P. Temperature calibration was taken as correct. The Leeds and
Borthrup type K potentiometer was found badly in meed of repair, so
a regular Leeds and Borthrup student potentiometer was used
instead. It was found to work very well.
The Compressed Air Agitator.The compressed air agitator used by
Rhodes was left un
changed. Regulation of the temperature was done manually instead
of by use of an automatic thermoregulator. *t was found that by use
of a slide wire, heat input could be balanced against radiation and
the temperature maintained constant within tl° as long as the
external E. M. F. did not vary. As a consequence the relay switch
was removed and replaced by a simple single throw switch.
Apparatus For Following Pressure Change, etc.Plate I is a
diagram of the apparatus, all glass being
of pyrex. lost of the external tubing is of small bore
capillary. A is the thermocouple and B is a tube conducting the
compressed air into the furnace. B, I, «T, K, L, P, Q, are
stopcocks, L and P being vacuum cocks. C is a bulb provided
-
f
with two stopcocks and is used to store the gas product® for
analysis. It is attached to the mercury pump E by a short piece of
rubber tubing. The mercury pump has a bulb of 250o.o. capacity at
the top and a leveling bulb attached below. It is comneete# to the
small glass mercury trap 0 by glass and rubber tubing. F is a short
glass tip whose use will be described later. H is a cooling tube
made by bending about 4 feet of 5 mm. tubing to form 4 XT’s and
then folding the 0f8 together ®o the whole will fit into a large
Dewar jar. The last two and a half U*s are filled with glass beads
to increase the surfaee and produce a turbulent flow. This is
connected by a series of stopcocks to the reaction bulb M which has
about 320 c.o. capacity. The reaction bulb is connected by small
capillary to the manometer R of capillary tubing and provided with
a leveling bulb clamped to a vertical rack and pinion so a fine and
rapid adjustment of the Eg level can be made. The upper portion of
the left arm of the manometer is enlarged so that if the Hg thread
breaks it can be run up into the enlargement and be brought
together again. B is a side arm with attachment (see B Detail) for
introducing sample as follows: The ampoule S is made of small
shellwall glass by sealing over the end of a three-inch piece.A
point about one inch from this end is heated around the
circumference until the glass is soft, and then the two ends arc
pulled apart until a fine capillary tube connect® then. This
ampoule is weighed accurately to l/lO mg. after which
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10
the desired weight of dimethyl carbonate Is Introduced through a
fine capillary funnel which will pass through the capillary of the
ampoule. The ampoule and eantente are put into a EaCX ice mixture
at about -15° to freeze the carbonate, a suction pump is attached
to the upper, the air is pumped off, the fine capillary sealed
through, and the two ends drawn a- part. Both ends are dried
thoroughly and rewelghed to l/lO »g. and the exact weight of the
carbonate obtained by difference. The ampoule thus filled is put
into the. upright tube of H and slipped through a platinum loop
sealed in a glass tube containing an iron core, f a s shown. The
upper portion of the upright tube is then closed over*
When the temperature is up to the desired value and the external
wires hot, cocks P, I, D are closed and the Bg in manometer R is
rum up to 0 mark and cock Q, closed. A Cenco Hyvae pump is attached
at K and the system evacuated. Then *2 from a cylinder is run in to
atmospheric pressure through
K and the system re-evacuated. Cocks J, L, K are then closed.
The manometer bulb is lowered until, with cock Q, open, the Hg
level in the left arm is at zero. The meter stick from which the
pressures are read is adjusted so that its lower, zero end is
exactly opposite the lower level of the Hg In the right arm, and
clamped in place by means of wing nuts on bolts passing through two
slots in the meter stick. Cock G is closed and the Hg in the right
arm raised to a level
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II
corresponding approximately to the expected initial pressure•
fhe whole of H is now carefully heated with a flame• A solenoid,
connected to 110 v. circuit with a tap key and resistance in
series, is slipped over the arm of E containing the glass-covered
iron core T and the circuit closed hy a single tap on the key,
thereby causing the platinum loop to strike the capillary of the
ampoule a sharp blow and break it. The carbonate at once passes
into the reaction flask and a stop watch started. The whole of H is
again heated by a flame and then sealed eff from the connecting arm
as close to the external heating wires as is feasible. At periodic
intervals Q, is opened* the leveling bulb adjusted so the Hg in the
left arm is at 0 and the pressure read off the meter stick at the
point opposite the level of the Hg in the right arm. Both the time
and the eerresponding pressure are recorded.
At the end of the rim the level of the Hg in the left arm of the
manometer is run down to the end of the external heating wires,
cock Q, is closed, and cocks J and I opened, thus allowing the
vapors to pass through the ti tubes S which are cooled by dry ice
and alcohol to -80°C. in order to remove UBdeoomposed carbonate.
(Although dimethyl carbonate freezes just above zero, it was found
that it could not be completely removed by using EaCi ice mixture
at -170C.}. Cock D is opened to the system and the gas pumped into
E by lowering the leveling bulb and then, after reversing Cock D,
it is delivered into the,storage bulb C which has just been
evacuated.
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12
Several pumpings are necessary to cause a complete evacuation of
the eyete*. Korever HcHO, which is one of the produets of pyrolysis
condenses in part in U tubes and must he pumped out. Cook 3 is now
closed and K opened to the atmosphere.A water pump is attached to
cock T which is opened, and any eondensed Hg or vapor in the
capillary leading to the manometer is drawn out.
If the amount of condensed ester is to be determined, the dewar
containing the freezing mixture is removed from the U tubes. Two
tubes in series, one containing CaClg and one Mg(Cl04)2, are
attached to F by a short length of pressure tubing; The tubes are
evacuated with the Hyvae pimp and filled with Ug* Another tube
containing CaClg is attached to a small TJ tube which is connected
to I by pressure tubing.This CaClg tube and U tube are evacuated
and filled with Hg
and the U tube immersed in dry ice-alcohol mixture. The tip of F
is broken off, cock I is opened, and a slow stream of air drawn
through the U tubes by applying suction to the CaClg
tube attached to the single XT tube in the freezing mixture.The
ester condense® In this XT tube. When the ester is removed from the
regular XT tubes this smaller XT tube is raised out of the freezing
mixture until only about the lower inch remains immersed. After the
ester in the higher part of the tube has melted and recomdeased at
the. bottom both arms are sealed off. The weight of the ester is
determined by weighing
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1#
the tabe eontaining ester and air and them breaking it, removing
the ester and reweighing. The amount of ester is obtained by
differsme*.
To begin a new run F is resealed, H is resealed on to its side
arm from the reaction flask* and the above procedure repeated.
After as much of the products has been collected in C as is
desired, it is removed from the apparatus and the gas analyzed on
the Orsat gas analysis apparatus.
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14
Qualitative Analysis of the Profluotg
Since Tostado5 did not actually make "any qualitative testa for
possitl® predmets, it seemed desirable to have some specific
evidence of the presence or absence of different products
suepeetefl to be formed* In order to obtain products for analysis
ampoules containing about.08 gm. carbonate were put into pyrex
tubes of about 90 c.c. capacity, 'thsst tubes sere evacuated,
sealed off, and the ampoules broken by shaking the tubes violently.
These tubes were held in a sheet iron cage and lowered into the
furnace which was kept at about 500°C. After several hours the
tubes were removed. It was noted that all tubes had some deposit of
carbon, especially on the part deepest in the furnace.
Dimethyl other. Since dimethyl ether was to be determined by the
method given by Schor&er9 it seemed desirable to determine the
lower limit of sensitivity of the method. According a quantity of
ether was generated and dissolved in HgSO^ by the method described
by Vanino.*0. The gas was regenerated by diluting the acid solution
in water and running the gas through a CaClg tube into a gas buret.
By continual dilution with air
it was found that when one c.c. of a 5$ mixture was dissolved in
a few c.c. of cold water and tested the lower limit was reached for
a satisfactory test. At 27° and 70 cm. pressure this corresponds to
about 0.0001 gm. ether.
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15
It has been shown by Dodge1"1" that dimethyl ether interferes
with the test for alcohol, and since Schorger’s method eonverte the
ether into alcohol much time was lost and uasmtiefaetory results
obtained at the beginning of the experiments because of ignorance
of this interference.
Attempts were made to separate the carbonate from the gas by
freezing. To determine the effectiveness an ampoule containing
about .08 gm. was put into a 90 c.c. tube which was sealed with air
in it. The ampoule was broken and the tube immersed in HaCl-lce
mixture at -17° for £ hour. The tube was broken open and the gas
pumped off while the tube was still immersed. This gas was
dissolved in 30 c.o. water.To 20 c.o. was added 5 c.c. of 10$ HaOH
and the mixture allowed to stand overnight in a stoppered flask.
The 25 c.c. resulting were distilled, 20 c.c. being collected and
redistilled into another flask, 15 c.c. being collected. This 15
c.o. was tested for methyl alcohol. A very weak but positive test
resulted, showing that the carbonate can be kept back almost
completely by freezing.
One of the tubes which had been in the furnace was immersed in
HaCl-ioe mixture for half an hour. It was then broken open and the
gas pumped off. The gas was run slowly into 25 c.o. water. Twenty
c.c. were taken and tested for methoxy with ester linkage. A
positive test was given.Since as above remarked, methyl ether would
break down and test with this treatment, it would seem to indicate
ether is
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I#
present in small quantities*A gas sample from the products of
one of the regular
kinetic runs was drawn into an evacuated flask. A few c.c. of
dilute HaOH containing HgOg was sucked in and the flask shaken
to dissolve ftestrof HCHO, After standing ten minute® or more,
the solution was run out, acidified, and the HgO^remaln-
ing destroyed with permanganate. Excess permanganate was added
and then destroyed with oxalic acid after about two to three
minutea. Schiff's reagent was now added. A definite positive test
resulted at onoe. This coloration could he due either to dimethyl
ether or dimethyl carbonate if it passed through the U tubes cooled
by dry ice-alcohol mixture, f® settle this latter point a 500 c.c.
bulb was evacuated, about half a c.c. of carbonate drawn in, and
the bulb filled with Wg to atmospheric pressure. This bulb was
attached to cock I
by rubber tubing and immersed in water at 45o-50°C* At this
temperature the carbonate has a vapor pressure of about 17 ©a.
After a few minutes the gas was pumped through the V tubes, cooled
in dry ice-alcohol, into another bulb C which had been evacuated.
The bulb C was removed, dilute HaOH containing HgOg run in, and the
contents thoroughly shaken to dissolve
and hydrolyse any carbonate present. HgOg was added with the
HsOE simply to make conditions more nearly similar to those in
the test on the gas sample. The solution was run out and treated a#
before, but a negative test was given, indicating
-
If
that ether is a product.Formaldehyde: One of the remaining tubes
was broken
open and the contents shaken with water. Two c.c. were taken and
tested for ECHO by the gallic acid test.13 A positive test was
given almost at once.
Acetone: Two c.c. of the above solution were taken andtested for
acetone.14 The test was negative.
AoeialSehy*®: Five c>c. of the above solution weretested for
acetaldehyde.14 The result was that a slight
. ' : ' , \ . .. . - - ' color developed whloh was Insufficient
to be considered positive. ■ • ' '-v.'. :• • : ■ : - - : - V
Carbon Monozifie;; A new tube was taken, broken open, and the
gas tested for CO by PdClg method.15 A positive test was. given.
..... , * ■ ' •■■■■ -• ■ • : - • • . ' . ̂ ■: y' i - ,
Carbon Dioxide: Considerable white precipitate wasformed when
some of the gas was shaken with BaClg. This pre
cipitate dissolved readily in HCl with efferveecenee. Hence COg
appears to be present.
Hydremiaj Ho specific test was made for Eg. It was ob-- : ' ' '
' - r ..' ' - ' - : . ' ' r\ Vserved, however, that water vapor
condensed out in the capillaries of the Great when the gas was
passed:through;the heated CuO tube, for the determination of Eg. .
1
Methane: Ho specific test was made for methane. After■■ ■ ‘ ; '
. . . ■the determination of COg, Eg, CO in the Great there always
re
mained about 25fj of the original gas volume which was
determined
-
as methane by eeabmstion with exygea.Ethanet Ho specific tests
were made for ethane, which
eight easily he present through the eombira tion of methyl mil**
eale. fostado claims to have fornid ethane ae a product to the
extent of a few per cent. Initial Onset analyses indicated the
presence of ethane,in this investigation hut it was later
discovered that this was Sue to CO not completely removed by
oxidation by CuO.. When a different CuO tube was used the per cent
of ethane came out consistently aero,
Illumlnants: The presence of illuminants was not ous-peeted
until late in the investigation when teats in which Brgwas absorbed
indicated the presence of unsaturated compounds. Specific testes on
the gas products showed that acetylene was was absent. Moreover,
when the gas was passed into a pipet containing fuming HgSO^ in the
Orsat, a small amount was absorbed, This was not due to the
solubility of other substances because more than four passings of
the gas into the pipet ̂did not increase the amount absorbed. The
illuminant was assumed to be ethylene.
Water: To determine whether or not water is a product,the U
tubes were opened and powdered, anhydrous cobaltous chlor lie put
in. When the products of the packed flask run were pumped through,
a small portion of the eobaltous chloride turned pink. This would
seem to indicate some water, but in very small amounts. Specific
test with ester shewed that it does not color eobaltous
chloride.
-
IS
Carbon: As remarked above, a carbon deposit was ebservedin the
tubes heated to obtain products for qualitative analysis. Moreover,
in the kinetic- runs it was observed that the pyres flask took on a
yellowish-brown hue which became progressively darker the longer
the flask was used.
Other products; Whenever the gas products were dissolved in
water a peculiar persistent sweetish odor was given off the
solution. Hone of the products identified have a similar odor. What
this substance is is not known. »' '
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20
QnantltatlTe Analysis of tho Reaction Products
For the purpose of making quantitative analyses» the IT.S.
Bureau of Mines Great apparatus for gas analysis17 was set up.
Several modifications of the procedure were found necessary on
account of poor totals and poor reproducibility of results {except
for absorbables) which were obtained when the procedure given was
used. This does not necessarily reflect adversely upon the Bureau
of Mines method, but may simply be due to characteristics of the
particular apparatus used.
A discussion of the more important modifications follows:1.
Absorbables. Absorbables include C02, HCHO and (CH3)20.
Instead of the 50$ KOH recommended by the Bureau, approximately
one normal HaOH was used. %iis was due to the fact that the
apparatus was used jointly by Fitzhugh who studied the pyrolysis of
dimethyl sulfite.18 Stronger BaOH interfered seriously ' : ' ' ■ "
■ ■ - : ' . : : ' . - , ' ^ - with his determinations of S02
gravimetrically from the solu
tion from the alkali pipette, The only disadvantage in the use
of dilute BaOH is that it is more short lived. The supply of alkali
for toe pipette was at all times kept under a gas mixture
consisting approximately of 20$ Eg, 35$ CO, and
45$ natural gas, which contained about 82$ methane and 13$
ethane. . ■ . . . ■ .
2i Hydrogen and Carbon monoxide. Hydrogen and; carbon monoxide
were determined by fractional combustion by Chp at
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21
500®. Si® Bureau’s pamphlet calls for a single combustion with
two passings each way at 10 c.c. per ■taut®. A single combustion
was found sufficient for the removal of hydrogen but a second one
was necessary completely to remove carbon monoxide. $he 00% formed
from the first combustion was ab
sorbed before the second one was made. It is known that CuO
absorbs CO and that CO is not completely oxidized unless it is
removed as soon as formed.19 This may account for the necessity for
a second combustion.
Any CO undetermined here will be determined as ethane in the
combustion plpet. This explains the source of ethane which feetado
reported and which was found in the earlier analyses of this
investigation.
3. Methane. Originally methane was determined as the Bureau’s
pamphlet directs. It was found by Fitzhugh,18 however, that the
freshly reduced CuO absorbed the oxygen added at the rate of 2 c.c.
per hour, thus throwing the readings off for the combustion of
methane. To obviate the need for running the oxygen through the CuO
tube, about 10 c.c. Eg
were run into the left side of the manifold before the addition
of oxygen, passed through the CuO tube to flush out the methane,
and then mixed with the gas sample in the gas buret. The cocks
leading to the CuO tube, now filled with Bg* were then closed.
The pamphlet calls for two combustions over the platinum
filament with several passings of the gas the first time, and once
the second time. When this was done, it was found that
\
-
the per cent of methane was almost invariably considerably less
than the per cent of original gas sample remaining after the
removal of absorbables, % and GO, thus indicatingIncomplete
combustion* 1© obtain good results, it was necessary to make three
combustions and to pass the gas over the platinum filament at least
ten times in each case.
Formaldehyde, Formaldehyde was determined iodometrical- ly,*2 A
sample of the gas was measured in the gas buret of the Great and
delivered Into an evacuated bulb. A measured amount of standard
0.01H I2 was rum in from a buret together with enough 0.15H HaOH to
produce a straw colored solution after considerable shaking. After
standing for about ten minutes the solution was run into a flask
and the bulb rinsed1several times with distilled water. %he
solution was acidified and the remaining 1% titrated with standard
0.01H Thiosulfate. The formaldehyde equivalent to the Ig
used can then be calculated and its per cent of the gas sample
obtained. In general values of only 0.2$ to 0.5$ were obtained.
Dimethyl ether. Though no quantitative determination of dimethyl
ether was made, evidence that it is present only in small amounts,
other than that obtained colorimetrieally, is the following: In one
of the Orsat analyses total absorbablescame out 32.35$. This would
include C02, HCHO, dimethyl etherand some carbonate. (Methyl
carbonate was present since in
-
this case HaCl-ice at was asei to eool the U tefcoe.It was later
shown to pass through at this temperature by a method similar to
that used to prove that the carbonate does not pass through the tf
tubes when they are cooled with dry lee and alcohol. This method
has already been described under the qualitative tests for dimethyl
ether.) A gas sample of 52.1 c.c.
-
24
Illuminantet Illuminante were determined by absorption in fuming
H2S04 .
Ester: The method of determining undeepmposed ester hasalready
been described, $he method.did mot seem highly accurate.
Total gas volumes The total amount of gas collected was. ■ ■ ■ ■
: v ;determined by measuring successive portions of the gas
volume
In the gae buret. By running mercury into the sample bulb, the
last few c.c. of gas could be forced over into the buret. In each
case the volume, temperature, and barometric pressure were
recorded*
-
25
A nttmtier of kinetic runs and corresponding analyses were made.
In some of the rune the U tubes were cooled with ice and salt
mixture which did not complete remove the ester* thus giving high
absorbablea and throwing She percentages of the other product# off.
fhem^ toot the analytical procedure in connection with the use of
the Great was not completely worked cut in earlier analyses, giving
poor reproducibility. For these reasons only the analytical results
of runs made after the experimental technique had been worked out
will be given. •' .- * Using a sample of about 0.2020 gm. ester,
four runs weremade to complete decomposition at 540 C. The kinetic
data are given in Table I and a graph given in Figure 2. The time
is given in the first column, and the corresponding pressures in
columns 2, 4, 6, and 8 for each run? Columns 3, 5, 7, and 9 give
the change in the pressure per minute for certain portions of the
reaction. The initial pressure was determined by extrapolation to
zero time. These may be considered quite accurate because the curve
is almost linear for the first few minutes. The ratios of the final
to the initial pressure sreas follows: p
Run 20
-
26
Since it appears that one molecule of dimethyl carbonate
decomposes into four molecules, it was expected that CO^,
Hg, CO, and CH^ would each total 25$. Actual analysis of runs 3
and 4 gave:
- - . . ' ' v. : : ? V / -i •'Bun 3 Run 4
$ Decomposition 100 100Initial ester 0.2024 gnu 0.2013 gm.
. is . ' $ ■■■ . ■ ■ ■;COg 25.8 ga.i°2H4 *S •**£ 26.8 27.6=0 ,
26.1 26.2
'v: Cl, ■ 22.9 22.5, *9t.l 99.9 100.1
HCHO 0.214*Ester usdee. ■ . --- ••• ' 'Gas vol. ohs. 242 c.c.
20?*4 * #.
- : Gas. vol. calc. 239 c.c. 238 c.c.. The value given for GOg
in. actually the total absorbable#
which includes HCHO and (CHg)gO. Since the error in
determining
the ebeorbables is of the erder of magnitude of the per cent
H
-
by four. For Run 3 the agreement can be seen to be excellent.
$he low result for the gas volume observed in Run 4 la probably due
to leakage through the cooks of the sample bulb.
faking the 4 to 1 ratio as indicative of a complete reaction,
three runs were then made to three quarters decompo- elties. For
each run, therefore, the reaction was allowed to proceed until the
pressure developed was 3.25 times the initial, pressure determined
by extrapolation, fhe kinetic data are given in Table II, and a
graph is given in Figure 3.
Analysis of the product® gave: .
deeomp. from volume ratio 79.7 Total ester 0.6056 gm.
*co2 26.4c2H4 - 1.0*2 24.4CO 24.1ch4 24.1Total 100J0ECHO
0.169#
Ester undec. .0810 gm.Gas vol. obs. 569 c.c. at 25° and 70.0
cm.Gas vol. calc.for total deeomp. 714 c.c. at 25° and 70.0 em.
le products cannot be removed instantaneously, the
-
28
reaction actually wont slightly beyond three quarters
decomposition. To determine the true degree of decomposition, the
volume which the 0.6059gm enter would occupy at 25° and 70.0 cm.
was calculated and multiplied by four. This is the volume which
would result if the reaction had gone to completion. By dividing
the observed volume by this, volume and multiplying by 1 0 0, the
true per cent was obtained.
Two series of runs to half decomposition were also made.The
decomposition was allowed to proceed until the pressure developed
was 2.5 times the initial pressure determined by extrapolation.
The kinetic data of the first of these is given in Table Ill and
graphed in Figure 4. The analysis of the mixed products of the four
rune gave:
% deoomp. from volume ratio 54.8 Total ester 0.8089 gm.
C02%n2COGH4TotalmemoEster undec. 0.3636 gm.Gas vol. obs. 523
o.c. at 25° and 70.0cm.Gas vol.calc.
for total decomp. 955 at 25° and 70.0 cm.The next series to half
decomposition consisted of two
28.8.8
' 23.822.4 '23.4 99.2
0.243#
-
g#
runs. The kinetic data are given in Table IY and graphed in
Figure 4. A composite analysis gave:
S& decomp* from volume ratio 63*6■Total, ester - 0.4030
gm.
GQg 32.6GeS* .6H 2 21.9GO 21.9% 23.3Total 100*3ECHO 0.135$Ester
undec. 0,1544 gm.Gas vol. oh®. 250 c.c. at 25® and 70.0 cm.Gas vol.
ealc. fortotal decomposition 476 c.c* at 25° and 70.0 cm.
The weight of ester was then reduced to about 0.1010 gm., and
three runs made to infinite time at 540°C. The kineticdata are
given in Table V and graphed in Figure 5. The following ratios of
the final pressure to the initial pressure were obtained, the
initial pressure being determined by extrapolation:
Run Po Pf K1 17.7 69.6 . 3.932 18.3 67.8 3.703 66.2 17.9
5.67
Run 3 was made with a new bulb which was first seasoned, by
making several runs in it and discarding the products..
Considerable variation in the ?f to P0 ratio Is observed.
ihai
-
30
faking the ratio as 5.7 and using the new bulb runs were made to
three quarters decomposition and to half decomposition as before.
Kinetic data and graphs are given in fables VI and VII and Figure 6
. In addition a run to infinite time was made with the same initial
pressure in a packed flask. She kinetic data and graph are included
in fable VIII and Figure #*
lack of time prevented analysis of any runs at this
lowerpressure.
-
31
Tables of Kinetle Data
She following symbols are used in tabulation of the data; t is
the time in minutes measured from the moment
of the breaking of the ampoule.P is the pressure produced in
centimeters of
t ' 'mercury at the time t.P is the change in pressure per
minute between the
value of P adjacent to it and just below it.
The temperature was 540°C.
-
gglgll
sassgs
tsgggŝ
igssss
KssPS'
0̂'m
to22£3455£678
TABLE ITotal Decomposition
Run 1 Run 2 3 Run0^2018g. 0 .201^ . 0.2024m. 0.20134.1 34.4 .
33.8 33.0.3f.3
38.1 37.637.139.240.2 39.9 41.5.41.4: 43.6■42^7 :;i.s
46,5 1.4
49.8 1.4
58.260*?
45.0 1.347.0 1.348.9 1.3
55.2 1.2
59.9
43.044.245.7 ■. • • • -47.048.2 49.550.711:154.1
t-v,.-
1.2- 45.5 1.5 47,4
1.2 50.6m m'.1,3:;:;;:55.5
■ 11:1
63,6 -V'.: 59.6 : v 66.4- " •• ‘ :66.0
66.068,0 66.1 ' 64.9 72.173.0 70.9 69.6 77.177*1 -v 76.7 . .
74.0 85.781.5 80.0 77.8 86.506*4 83.5 84.0 : 90.089,0 87.0 8S.2
92.892.0 M m 89.0 95.5'98.4M m .v:. v '93.3 91.1104,0 100.8 98.8
104.8
107.0 104.8 110.0115. . r 116.0 . 109.8 V 116.2117,8 114.9 113.0
; ; 115.5121.9 121.7 118.1 119.0125.0 124.6 121.3 120.8134,6
136.7 135.5
V -
-
SSSSSSgSSSggSgSKSKPS
'0
33
fiBLE IX
t0Li
3i
Hun 1 - Hun 2 Enn 30.2018 gm. 0.2020 gm. - 0.2018 iP 3P. ' ' ' ■
- P ■88.1 34.4 35.0
• 88.8 36.937.7 36.3 37.508.4 37.0 38.288%0 37.7 38.8■ ,v • 38.7
. 39.440.7 39.8 40.240.942.9 ' 42*4 41.7
K -S3.155.35919#&.#54.0 65.974.488.093.4 98.1
102.2196.0108.0110.4112.7114.0
45.048.2
'4-4 * .. • . ? '
56.058.4
64.566.6
104.5107.1 108.9,111.1 111.0
l56.588 T60,965.073.381.688.4 93.8
El108.9111.8113.5118.98
-
MILE III
0.2019Dgm.P A p
70,2 VV4.#
SO53&353640 f®,i4 H 82.8
One Half Run 2
0^2023
0,2021 mP A P
0 35.0 35.6.... 35.1 34.12 36.5 36.5 ■ 37.8 • 38.93 37.5 38.3
40.3 *4 38.9 40.8 43.2 ': • 44.05 40.5 43.0 1.7 45.3 - 46.56 42.3
1.4 44.7 2.0 47.4 1-9 48.97 43.f 1.4 46.7 1.6 4# j U # 51.48 45.1
1.4 48.3 1.8 #1^3 53.29 46*5; 1.8 50.1, 1.8 53.2 :.2 ;o 56.010 48.0
1.4 51.9 1.7 55.0 jl*8 58.011 49.4 1.2 53.5 1.7 56.9 i.g 60.012
50.t 1,4 55.2 1.8 58.6 l;7 62.015 52.0 1.3 : 57.0 1.4 60.0 x.*4
74.014 53.3V 1.3 58.4 1.4 61.5 1;5 65.715 54.4 1.3 59.8 1.4 63i0;
1.-5 67.420 60.3,r 1.3 67.0 1.2 71.1 1.6 74.925 45.f> 73.2 1.0
82.52® • • ... - >• ■" 85.2
Run 4 0.2026 m . P A p
2.5*2.4 2.8 2.8 2.8 * 2.0
• 2 . 0 '2%02.0leti:?'1.5
78.383.084.0
1.0rI#?5 87 *75
-
One Half DecompositionTABLE 17 .
Run 1 Run 20.2017 ga. 0.2013 gm
t i? A-B - P A po : •34.7 : 33.82 .. 37.1 . *7.0 .3 38.3 .4 39.4
. 40.25 ■ . 40.7 . 42.5g. • ■ 42 3 . 45.07 45.0 2.3 47.4-8 47.3 2.2
49.59 : 49.5 2.3 • 51&8 .10 : . 51.8 2.1 ‘ 54.1 1.911 53.9 2.2
56.0 2.112 56.1 2.1 58.1 1.913 52.2 2.0 60.0 1.8M . ■." €0.2 2.0
61.8 1.715 ’ ■•.'22. 2 '-1.8 63.5 1.620 71.3 71.725 79.0 78.630
85.5 . 84.5 " '31 86.75 - ;. .
-
ggggas
ggasgg
ssgsgK
SBggss
ssss:
O
, *
: ■
-V i '
H . '
> *.
36
TABLE VTotal Decomposition
0.1004t P0 17.72 19.73 20.74 21.95 23.16 24.37 -V'K - 23 48
23.79 : #7#10 . 28.911 go.0}2; ■ ■ 31*913 32.0
Ron 2 0.1015 &m.
Run 30.1006 i
v-'-;
w a34.0
Is38.039.089.740.041.3
1.1 l.l •1a 1 1*0 1*0 1.0 1*0 1*0 1*0 1*0 1*0 1*0 1*0
18.3 20.2 21.8 22*823.224.2:2 * 226.0.1?:?28.7
i i33*0 33* #34.83* #36.4II43.2':rv- «
1.0.9
1.0.91.01.0y:!.81.0
i i•8
a:
P17.920.221.4 1.322.1 1.023.7 1.024.7 1.025.7 1.026.7 1.027.7
•1.028.7 : .929.6 ' ,8 .30.431.232.032.7
36.3
39.3
46.4 44*0; . , : 42.1---49.2 ■ . 47.5:l!:::-:: 44.651.6 49.5
46.853.8 . 51.6. 49.155.6 53.757.1 55.5 _ ■ •58.4 56,8 ;; 53.161.4
56.065.0 ■ ' ■ 61.5 V I:':-' 58.063.9 62.7 58.864.6 63.4 60.069.6
67.8 66.2
-
TABLE VItoree Fourths BeooepttSitlon
16BO25m86404660656065VOf58084
0.1008 gtaA
52*0 54*5 56*8 88*1 41 E45*:i:4 4
?47*249.049*950.951.7..52*3
Run 20.1007 m.
88^38 i 6t s a
IS49.550.851.852.8
Run 30.1011 gm.
p- A P . P ^ P T ,17.3 - 17.5 17.819.1 19.8 20.0. 20.2 20.9 21.1
.21.1 21.9 22,3 :
■ •*' V : 22.1 .7 22.8 .8 23.1■ 22.8 .8 23.6 .8 24.0 -23.6 .7 •
24.4 .8 25.0■ ■ 24.5 V *8 ■ 28*2 g8 25.726.1 .8 26.0 .7 26.5' 26.9
>5 26.7 .7 ; 27.6% * .7 29^4 y *8 28.4•• 29.1 .9 28.2 .6
29.228.0 - .4 ' • ■ 28.8' .7 30.028.4 *9 • ' 29.5 .7 30.6- 29 *1 '
50*2, 31.5
.91*0
.7
.81.1
I38.040.745*048.847.048*450*051.252.255.153.7
-
38
TABLE VIIOne Half Decomposition
Run 1 Run 2 Run 3' 0.1020 gm. 0.1013 gm* 0.1020 gm.
t P Zxp P ^ P P /&P© ' 17.7 1.0 17.9 17.92 5 19.7 1.0 20.2
20.53 20.7 1.1 21.4 21.84" ’ ‘ 21.8 1.0 22.5 1.2 23.25 22.8 1.0
23.7 1.1 24.2 1.36 ’ 23.8 .9 • 24.8.- , .9x ■ 25.6 1.07 . % 24.7 ;$
25.T 1.0 28.5 1.08 ‘ . 25.3 - .9 .• ' 26.7 1.0 27.5 1.09" 2S.2 .9 -
27^7 ;8 28.5 1*010 27.1 .8 " 28.5'-/:i9: - 29.5 1.011 : 27.9 .7 • '
29;4;- ' 30.4 •9■IS- 28.6 .7 31.4 .913 29.3 .8 ' - 31.2 .8 ■ ■
32.114 30.1 .7 33.115 30.8 ’ • 32.8':v:::v''- 33.9 ' •• '.2d 34.1 .
- 36.3/ 37*8 - -25 ■ :3f.2;., 39 ̂6 .. 41*027 - . ‘ . - 42.1 1 ..29
■' • . ' . ' . 42*1 .30 ’ 40.0 *% 41.6 ‘ ' .;; :
-
"SEil°5SSS"§
"88°"K5gps'or
o":,
-
1
-
St) X3 20 JLJ- **> »•* *
-
p:
D je*t*r* T ^z. _2 T d /?***} 3
yÔ
-
/f
afa-t/e ma
-
P&**rj
j z m or
y/*,x Tmi/rMT
-
y y y , l □ Z « e r > y y Z< # e .
-
i
B
-
40
Discussion and Conclusions
As the graphs indicate there is considerable variation in the
velocity of the reaction for different runs. In some cases
duplication of runs was almost exact, as Figures 3 and 4 (right)
show. On the other hand, as can be seen in Figures 4 (left), 5
(right), and 6 , the reaction went progressively faster for other
runs. In addition several cases were observed in which the reaction
slowed down. Figure 7 and Figure 5 (left) being examples. Moreover,
the velocity of the first run of a day invariably proceeded more
slowly than the last run of the day before. The run in the packed
flask shows clearly a more rapid rise in pressure during the early
stages of the reaction than in an unpacked flask# All these facts
indicate some heterogeneity in . the reaction.
Inspection of the tables shows that in many cases the change in
pressure per minute is strictly linear over a period of several
minutes in the earlier part of the reaction. Such pressure
variations are characteristic of zero order reactions, which take
place on the wall of the reaction bulb.
At one time an apparatus was used in which the ester was
introduced into the reaction bulb through a stopcock. The
temperature was 510*0. After a few runs were made, the reaction
suddenly stopped. Though the ester was heated for half an hour, no
pressure change was observed. This behavior was repeated for five
runs* To force a reaction, the
-
4 1
temperature had to he raised to 550*0. where peculiar curves
were obtained, one of which is given in part in Figure 8 .The
behavior observed was presumably due to stopcock grease washed into
the system by the ester and seems to us to be proof that .the
initial decomposition of dimethyl carbonate is heteregeneon#.
The reaction graphed in part in Figure 8 proceeded for ten
hours, so practically all ester must have been decomposed. Hence,
any ester passing through the XT tubes which were
O ' 'cooled to -17 C. with ice and salt was negligible. Analysis
of the products gave:
C08 23.2*2 27.3eo 23,2% 1.13ch4 23.30Total 97.13
When the per cent of CO and CH4 is corrected on the assumption
that the ethane is due to CO, we have
co2%
23.20= 2 27.3000 . 24*88ch4 24.43
99.26Total
-
Ae has already been shown, dimethyl ether appears to he a
product of the reaction. It would seem plausible, therefore, that
the initial, heterogeneous decomposition ef dimethyl carbonate in
given by the equation
(CHgigCOg --5 (CEgigO+COg
Hinsehlwood and Askey20 have shown that dimethyl ether
decomposes homogeneously and unimoleeularly at temperatures , from
422°C. to 552*0. provided the initial pressure is above 800-400 mm.
The products were and CO, with ECHO asan intermediate product.
Furthermore, Fletcher22- has shown that formaldehyde decomposes
homogeneously and bimoieculariy from 510° to 607° when the initial
pressure was between 30 and 400 mm. The products were CO and Ho. -
.
In the present investigation it has been shown that for-
maldehyde is a preduet of pyrolysis and that neither formaldehyde
nor dimethyl ether accumulate to any appreciable extent. The latter
is to be expected since the temperature at which the decomposition
of the carbonate was studied was 540®C. Moreover, the analytical
data shows that COg, CO,
H2, and CH4 are the principal products of pyrolysis, each
being present to the extent of approximately 25^. It thus
appears that the principal decomposition of dimethyl carbonate can
be represented very nearly by the three consecutive reactions
42
-
43
(CHg} gC Og—— {CHg} gO COg
(CE3)20 — > H m o V C H 4m m o — > h 2+ go
That c62> CO, Hg, and CII4 are not present to the extent©f
exactly 25$ is probably due to site reactions which are un-
q.ueetionably present. Carbon ant ethylene are among the produets
formed, and water may also be. Prom the hiis tic data for the
peeked flask run, it will be observed that a decrease in pressure
of 7.9 cm. resulted over the period from 17& hours to 48 hours.
When the flask was removed from the furnace, the glass tubes used
to pack the flask and the flask Itself were observed to be very
dark yellowish-brown in color. The same color resulted with the
unpacked flask, but to a lesser degree. Hinshelwood and Askey21
found that dimethyl ether gives neither ethylene nor water. Hence
It appears that the products of pyrolysis undergo reaction at the
temperature used* In addition, of course, dimethyl carbonate may
decompose by some side reaction to give products other than those
already indicated.
Inspection of the analyses brings out the following facts: 1.
During the early stages of the reaction C02 is
present to more than 25$ of the gas volume and decreases with
time to less than 25$. 2. Eg and CO both begin at less than
25$ and increase to greater than 25$ with their ratio
remaining
-
44
nearly constant. S. The per cent of CH4 Is nearly constant*
In addition It will be observed that in the case of the
decomposition to 52.5^ completion, the per cent of CH^ is
greater than the per cent of either Hg or GO.
faking the mechanism as postulated and assuming that both
tCH3)gO and ECHO accumulate to the extent of 1 , 3 analysisshould
give
: ■ ' . 3 5Abeorbables 20.6 includes COg, (CHglgO,
Hg 23.4 • • -• ' :* -CO 23.4CH4 2 M
100.0
This is in good agreement with the values obtained for the
decomposition to 54.8^ completion. However, in no case was there
any evidence that either the ether or formaldehyde was present to
more than a third, af that assumed eteve*
The ethylene formed is probably produced by the reaction
sch4 — * c2h4,h 2
which ha® teen studied by CanteloSS who passed CH4 through a hot
tube at 600°C*
Bone and Coward24 have observed that methane decomposes to give
carbon and hydrogen.
-
45
. CH4 — > C 4-282
They found, however, that the rate was very slow at temperatures
helow ?O0®C* enlees a very large surface was exposed to the gas.
This reaction would aeeeuat for some of the carbon formed as well
as a portion of the increase in Eg. They have
also shown that ethylene gives carbon and methane in the
neighborhood of S80®6#
c2k4 **> ̂ 4 CH4
In this manner some of the methane would be restored.Carbon
dioxide maybe removed by the reaction
COg + C — ) 2C0which is known to proceed slowly below 800°C. ,2^
or. by thereaction . ' • . . ' . .' : • ■
COg^Hg — » CO + EgO
which is favored by heat.2^It may be that a 'water gas* reaction
is also present
C + H 20 — > C04-H2
This series of reactions, known to proceed sore or lees rapidly
at the temperature used, provide a means of increasing the
percentages of CO and Eg and reducing the percentage of
Y/hat reaction causes the decrease in the volume is not• V
-
46
definitely known. However, a reaction such as Hgf CO— >C4
HgO
would have this effect. In any case, the reaction does Involve
the deposition of carton.
An estimate of the overall order of the reaction can be obtained
from the following consideration®s For a first order reaction, the
ratio of the time for three quarters decomposition to that for half
deeowpesitlon is 2 . For a second order reaction this ratio is
3.
It will he observed that Hun 8 in Table II and Run 4 in Table
III proceeded at about the same rate. Hence
4 * T0.T5 '28 2.6These runs were at the higher initial
pressure.
Again, Run 3 in Table VI and Run 1 in Table VII, both at the
lower Initial pressure, show about the same speed* Per this
case
Bti
— IL.83.26 2.3
which is in good agreement with the former value. These value®
indicate that the overall reaction is therefore between a first and
a second order.
-
1, An apparatus has been described which is suitablefor the
study in the gaseous phase of substances which are liquids at
ordinary temperatures. . :
2. Kinetic data have been obtained for the decompesl- ti@n of
dimethyl carbonate at 540°C. and at initial pressures of about 17.7
cm. and 34.0 cm.
g. Qualitative analyses have been made indicating that the
products are C02, CO, Eg* CH4 » c2̂ 4» HCHO, (CHsJgO^ C,H20, and
some unknown substanee. Acetylene, acetaldehyde*
\ ■ ■ ' -acetone and ethane are absent.4. Quantitative analyses
have been made to determine
the ratio of the components of the products at three stages of
the decomposition.
5. Evidence has been given to show that the reaetien Is in part
heterogeneous and in part homogeneous.
6 . A mechanism has been postulated to account for the facts,
but not entirely successfully.
7 . It has been shown that side reactions involving the products
take place. Known reactions are given which w i n produce results
which are in qualitative agreement with the facts.
-
48
Bibliography
1. Hlnehelwood, C. B.Kinetics of Chemical Change in Gaseous
System#. BrflE4 •» P • 2 *
2. Jellinek, Karl .: ' . . . . ' - • ' ' - , ■ 'Lehrbuch
flerPhyBikalischen ohemie I. Band (1914).p. 207 ff.
5. Hlnehelwoofl, C. II.Op. cit., p. 19.
4. ‘ Hlnshelwood, C. I?.Op. cit.. p. 187.
B. Alvares-Tostado, Claudiothermal Decomposition of Dimethyl
Carbonate. Master's Thesis, University of Arizona, 1955.
6 . Rice, F. 0 . and Johnston, V. R.J. A. C. S. 56, 214 (1934).
.
7. Findlay, AlexanderPractical Physical Chemistry. 6th Ed., p.
65.
8 . Rhodes, H. D.Thermal Decomposition of Dimethyl Sulfite.
Master's Thesis, University of Arizona, 1936.
9. Bchorger, A. V/.The Chemistry of Cellulose and Wood. 1st Ed.,
p. 527.
-
49
10. Vanino, LudwigPraperatlve Chcmie, Tol. II, 2nd Ed., p.
49.
lie Lodge, Barnett F.Analytical Ed. lad. and Eng. Chem., Vol. 4,
Ho. 1* p.28 (1932).
12. Treadwell, F. P., and Hall, T. H.Analytical Chemistry, 7th
Ed., Vol. II, p. 589*
13. Weston, $*. E.A Sehome for Detection of Organic Compounds,
3rd Ed., p* 47. . . .
14. Weston, F. E*Op. cit., p. 46. .
15. Treadwell, E. 2. and Hall, T. H.Analytical Chemistry, 4th
Ed., Vol. I, p. 506, footnote.
16. Snell, F. 0, and Snell, C. T.Colorimetric Methods of
Analysis, Vol. II, p. 1 (1937).
17. Fieldner, A. C.; Jones, G. W.; and Holbrook, V/. F.The
Bureau of Eines Orsat Apparatus for Gas Analysis. Technical Paper
Ho. 320, U. S. Department of Commerce.
18. Fitfchugh, Andrew F. , . .The Pyrolysis of Dimethyl Sulfite.
Master's Thesis, University of Arizona, 1936. .
19. Lunge, GeorgeTechnical Gas Analysis. Revised By H. R.
Ambler, 1934. pp. 145, 146.
:Udi*53
-
20. Hinshelwoofl , C. II., anS Aslcey, P. J*Homogeneous
Reactions Involving Complex Molecules. .Kinetics of Decomposition
of Gaseous Dimethyl Ether. Pros. Roy. Soc. A 115, IS27, p. 215.
21. Fletcher, C. J. 1£.The Thermal Decomposition of
Formaldehyde. Free. Boy. See. A 146, 1934, p. 367.
22. Cantelo, R. C.The Thermal Decomposition of Methane. J. Phys.
Chem. 28, 1924, p. 1036.
24. lone, V/. A., and Coward, H. P.The Thermal Decomposition of
Hydroearhons. I. J. Chem. Soc. 93, 1908, p. 1197.
26. Kendall, .Tames .Smith’s Inorganic Chemistry, 2nd Revised
Ed., p. 570
26. Partington, J. R. .Textbook of Inorganic Chemistry, 4th Ed.,
p, 687. .
50
-
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